[coreboot-gerrit] Patch merged into coreboot/master: 886d29b gpio: Remove non-ternary tristate mode, make ternaries easier

[gerrit at coreboot.org]

the following patch was just integrated into master:
commit 886d29bcd808476e0e83f68e3f7905fba4304b0a
Author: Julius Werner <jwerner at chromium.org>
Date:   Wed Sep 24 15:40:49 2014 -0700

    gpio: Remove non-ternary tristate mode, make ternaries easier
    
    The function to read board IDs from tristate GPIOs currently supports
    two output modes: a normal base-3 integer, or a custom format where
    every two bits represent one tristate pin. Each board decides which
    representation to use on its own, which is inconsistent and provides
    another possible gotcha to trip over when reading unfamiliar code.
    
    The two-bits-per-pin format creates the additional problem that a
    complete list of IDs (such as some boards use to build board-ID tables)
    necessarily has "holes" in them (since 0b11 does not correspond to a
    possible pin state), which makes them extremely tricky to write, read
    and expand. It's also very unintuitive in my opinion, although it was
    intended to make it easier to read individual pin states from a hex
    representation.
    
    This patch switches all boards over to base-3 and removes the other
    format to improve consistency. The tristate reading function will just
    print the pin states as they are read to make it easier to debug them,
    and we add a new BASE3() macro that can generate ternary numbers from
    pin states. Also change the order of all static initializers of board ID
    pin lists to write the most significant bit first, hoping that this can
    help clear up confusion about the endianness of the pins.
    
    CQ-DEPEND=CL:219902
    BUG=None
    TEST=Booted on a Nyan_Blaze (with board ID 1, unfortunately the only one
    I have). Compiled on Daisy, Peach_Pit, Nyan, Nyan_Big, Nyan_Blaze, Rush,
    Rush_Ryu, Storm, Veryon_Pinky and Falco for good measure.
    
    Change-Id: I3ce5a0829f260db7d7df77e6788c2c6d13901b8f
    Signed-off-by: Patrick Georgi <pgeorgi at chromium.org>
    Original-Commit-Id: 2fa9545ac431c9af111ee4444d593ee4cf49554d
    Original-Change-Id: I6133cdaf01ed6590ae07e88d9e85a33dc013211a
    Original-Signed-off-by: Julius Werner <jwerner at chromium.org>
    Original-Reviewed-on: https://chromium-review.googlesource.com/219901
    Original-Reviewed-by: Aaron Durbin <adurbin at chromium.org>
    Reviewed-on: http://review.coreboot.org/9401
    Tested-by: build bot (Jenkins)
    Reviewed-by: Stefan Reinauer <stefan.reinauer at coreboot.org>


See http://review.coreboot.org/9401 for details.

-gerrit